A 32 inch flat screen was embedded in a coffee table and covered by a protective layer of glass. Sensors around the edge of the glass surface need to be able to detect the precise location of an object on the glass so that a mouse cursor can be controlled with a stylus.

What sensors would you use to ensure accuracy of stylus location above the screen?

  • 1
    "precise" doesn't mean much - you should be more specific and define the desired spatial resolution: what is the minimum distance you need to discriminate? Commented Apr 26, 2016 at 19:01
  • Perhaps I didn't state a level of accuracy because I wanted to encourage a wider range of replies @igorStoppa. Unfortunately this also encourages your not very helpful reply. A minor side effect.
    – Hooperstu
    Commented Apr 26, 2016 at 19:08
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    The helpfulness of the replies you receive is correlated to the precision of the questions you ask. If you are open to a wide range of options, you should say so, instead of intentionally asking vague questions, hoping that they will bring a variety of solutions. My previous reply was meant to show you how to ask better question. Commented Apr 26, 2016 at 19:14
  • It sounds like you want a glass capacitive touch screen like on a tablet. While you can get them this large, you usually have to buy the monitor already integrated with the capacitive touch screen. I have never seen it were people add the capacitive touch screen afterwards.
    – st2000
    Commented Apr 27, 2016 at 4:59

1 Answer 1


Perhaps if you drop the monitor an inch or 2 away from the glass you can use a Frustrated Total Internal Reflection (FTIR) IR scheme. But at that shallow angle it will be tricky and may require several cameras around the edges.

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added later...

Should mention the parallax problem given there is a gap of an inch or more between the monitor and the touch screen. FTIR is better when you project the image onto the touch screen.

If you don't mind lower resolution, I believe the micro dose dispenser soda machines use a capacitive touch wire mess embedded in the transparent plastic front panel. Although micro dose dispensers appear to only need to emulate about 100 to 200 buttons. Not enough to control a mouse with any accuracy. But enough to control a GUI designed with such constraints.

Loose high resolution capacitive touch screens can be bought with out a monitor. However they tend to be much smaller then 32 inches.

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